How to wait for a stream to finish piping? (Nodejs)

Question

I have a for loop array of promises, so I used Promise.all to go through them and called then afterwards.

let promises = []; promises.push(promise1); promises.push(promise2); promises.push(promise3);  Promise.all(promises).then((responses) => {   for (let i = 0; i < promises.length; i++) {     if (promise.property === something) {       //do something     } else {       let file = fs.createWriteStream('./hello.pdf');       let stream = responses[i].pipe(file);       /*          I WANT THE PIPING AND THE FOLLOWING CODE           TO RUN BEFORE NEXT ITERATION OF FOR LOOP       */       stream.on('finish', () => {         //extract the text out of the pdf         extract(filePath, {splitPages: false}, (err, text) => {         if (err) {           console.log(err);         } else {           arrayOfDocuments[i].text_contents = text;         }       });     });       } } 

promise1, promise2, and promise3 are some http requests, and if one of them is an application/pdf, then I write it to a stream and parse the text out of it. But this code runs the next iteration before parsing the test out of the pdf. Is there a way to make the code wait until the piping to the stream and extracting are finished before moving on to the next iteration?

Answer 1

Without async/await, it's quite nasty. With async/await, just do this:

Promise.all(promises).then(async (responses) => {   for (...) {     await new Promise(fulfill => stream.on("finish", fulfill));     //extract the text out of the PDF   } })